sigma-rules/rules/windows/execution_shared_modules_local_sxs_dll.toml

[metadata]
creation_date = "2020/10/28"
integration = ["endpoint", "windows", "m365_defender", "sentinel_one_cloud_funnel", "crowdstrike"]
maturity = "production"
updated_date = "2025/08/26"

[rule]
author = ["Elastic"]
description = """
Identifies the creation, change, or deletion of a DLL module within a Windows SxS local folder. Adversaries may abuse
shared modules to execute malicious payloads by instructing the Windows module loader to load DLLs from arbitrary local
paths.
"""
from = "now-9m"
index = [
    "winlogbeat-*",
    "logs-endpoint.events.file-*",
    "logs-windows.sysmon_operational-*",
    "endgame-*",
    "logs-m365_defender.event-*",
    "logs-sentinel_one_cloud_funnel.*",
    "logs-crowdstrike.fdr*",
]
language = "eql"
license = "Elastic License v2"
name = "Execution via local SxS Shared Module"
note = """## Triage and analysis

The SxS DotLocal folder is a legitimate feature that can be abused to hijack standard modules loading order by forcing an executable on the same application.exe.local folder to load a malicious DLL module from the same directory.
"""
references = ["https://docs.microsoft.com/en-us/windows/win32/dlls/dynamic-link-library-redirection"]
risk_score = 47
rule_id = "a3ea12f3-0d4e-4667-8b44-4230c63f3c75"
severity = "medium"
tags = [
    "Domain: Endpoint",
    "OS: Windows",
    "Use Case: Threat Detection",
    "Tactic: Execution",
    "Data Source: Elastic Endgame",
    "Data Source: Elastic Defend",
    "Data Source: Sysmon",
    "Data Source: Microsoft Defender for Endpoint",
    "Data Source: SentinelOne",
    "Data Source: Crowdstrike",
    "Resources: Investigation Guide",
]
timestamp_override = "event.ingested"
type = "eql"

query = '''
file where host.os.type == "windows" and file.extension : "dll" and
  file.path : (
    "C:\\*\\*.exe.local\\*.dll",
    /* Crowdstrike specific condition as it uses NT Object paths */
    "\\Device\\HarddiskVolume*\\*\\*.exe.local\\*.dll"
  )
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1129"
name = "Shared Modules"
reference = "https://attack.mitre.org/techniques/T1129/"


[rule.threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"